Clockwork balance having an adjustable momentum of inertia



July 26, 1966 c PERRQT-AUDET 3,262,260

CLOCKWORK BALANCE HAVING AN ADJUSTABLE MOMEN'IUM 0F INERTIA Filed June 11, 1964 U i States a e 1 Claim. (cuss-107 Clockwork balances having an adjustable momentum of inertia 'are'well-known and allow an accurate ad ustment' of the clockwork operation. In such known bal- 1 ances the adjustment of the elastic momentum of the balance spring by means of an index or regulator is replaced by means adjusting the momentum of inertia of the balance. inertia of the balance is ensured by a translational or rotary movement of weights arranged diametrically to either side of the balance staff and at equal distances from the latter.

Thus, it has already been proposed to shift two diametrically opposed weights along the diametrically extending balance rim; in the prior arrangements said arm may be angularly shifted for this purpose with reference to the balance rim, or else, a lever may be pivotally secured to the balance staff so as to shift when moved projections raised on said weights and engaging a slot formed in said lever along an oblique or incurved line.

In other prior embodiments of clockwork balances having adjustable momentums of inertia, the masses are secured directly and pivotally to the rim of the balance so that their angular shifting may lead to a corresponding radial shifting of their centers of gravity with reference to the balance staff.

All these prior known embodiments show the drawback consisting in that the pivotal positioning of a lever on the The increase or decrease of the momentum of balance staff, which levers extend over the diametrical balance arm, or else, the arrangement of incurved parts which must be shifted with reference to the balance rim lead to serious difiiculties in the, execution of the balance and, furthermore, do not allow an easy common adjustment of the weights associated with the balance. Further, the shifting or rotation of the masses with reference to the balance is not easily and accurately executed when it is desired to modify the momentum of inertia of the balance.

My invention has for its object to remove these draw backs of prior balances having an adjustable momentum of inertia. To this end, I provide two regulating members revolvably secured to the balance at equal distances from the staff and facing the latter to either side thereof, the ends of said regulating members carrying heavy weights and being interconnected by two parallel members acting as connecting rods, last-mentioned parallel members being pivotally secured to the regulating members at opposite ends thereof, so that upon rocking of one regulating member round its pivotal connection with the balance, the other regulating member rocks simultaneously by the same angle, so that the centers of gravity of both regulating members move by equal extents towards or away from the-balance staff.

The accompanying drawings illustrate by way of example a preferred embodiment of my invention. In said drawings:

FIG. 1, is a view from above of my improved balance.

FIG. 2 is a cross-section along line IIII of FIG. 1.

The balance illustrated includes an outer annular rim 1 playing the part of a fiy wheel and showing a comparatively large momentum of inertia with reference to the balance staff axis. Said rim is secured to the balance staff 2 through the agency of two arm sections 3 extendice ing in opposite directions along a diameter of the staff 2. The rim 1 and the arm 33 form the balance of a clockwork.

Each arm section 3 is provided in the vicinity of its connection with the rim 1 with an opening into which is inserted with slight friction a regulating member 4 secured by means of a rivet 5 and washers so that it may be rocked against friction. Each regulating member ismade of a thin stamped sheet of metal and said members are given a generally incurved shape, the curvature being equal to or larger than that of the rim 1.- Each regulating member carries to one side of the securing rivet a shorter arm and on the other side a longerarm the outer end of which is enlarged so as to form a heavyweight 6.

The two regulatingmembers 4 are interconnected by two parallel connecting rods 7 and8. These two rods 7 and 8 are pivotally connected at their ends with the corresponding regulating member as provided advantageously by rivets engaging corresponding openings in said regulating members with the interposition of washers.

In order to prevent any contact between the upper surfaces of the regulating members and rods 7 and 8 on the one hand and the lower surface of the hairspring of the balance, which is not illustrated, said regulating members 4 are given a suitablevertically incurved outline. Y Y

A reference mark 9 constituted for instance by a projection on the lateral surface of at least one regulating member, facing the balance staff cooperates'with a corresponding scale carried, underneath the path of said mark or projection 9, on the arm 3 so as to define the position of the regulating members with reference to the original position defined by a sub-division of the scale. It is thus possible to obtain an adjustment in a positive or negative direction. The projection 9 forming the reference mark can obviously be provided as well. on the other side of the rivet 5,.that is on the surface of the regulating member facing outwardly with reference to the balance staff.

When the balance oscillates round its axis, the regulating members and the weight 6 carried thereby lie in a well-defined position and are held in said position frictionally by the rivets -5. The balance assumes thus an accurately defined momentum of inertia and it rocks with a eontant frequency which may however be too small or too large. Consequently, it is necessary to adjust the momentum of inertia of the balance and this is obtained by angularly shifting the regulating members so as to increase or decrease the distance of the parts of said members carrying the weights 6 with reference to the stafi 2, whereby the momentum of inertia is correspondingly increased or decreased. The connection provided by the connecting rods between the regulating members ensures the symmetrical position at any time for the two I lengths of their sections and the amplitude of the adregulating members, the adjustment of one regulating to be grasped by tweezers, or else, I may provide a small opening adapted to be engaged by a pin.

On the other hand, the adjustment may be executed by means of an instrument of which the operative section may engage a part of the regulating member with a view of adjusting both regulating members. In principle, it is necessary to stop the balance to adjust the momentum of intertia and to maintain its balanced conditions during such an adjustment.

The size of the weights on the regulating members, the

I Lastly, it is possible to replace the connecting rods 7 and 8 by wires of a reduced cross-section and the ends of which are bent so as to form eyes connected by rivets with the corresponding sections of the regulating members.

My improved balance distinguishes through its structurally simple execution, easy assembly and highly convenient and accurate adjustment while said adjustment may be obtained without any dismantling of the balance pivotal by means of very simple tools such as tweezers or a needle point, this leading to a very high accuracy. I also prevent any further assembly within the restricted area underneath the hair spring.

What I claim is:

In a balance having an adjustable momentum of inertia including a balance staff, a balance arm and a balance (A) two arm sections extending in opposite directions along a diameter of said staff securing said rim to said staff; each arm section having an opening near the point of attachment thereof with the rim; at least one section having a scale near said point of attachment;

(B) a regulating member consisting of an incurvedsheet of metal having a curvature at least equal to that of the rim movably mounted in each of said openings;

(C) each member having a short arm and a longer arm; said longer arm having an enlarged end forming a weight;

(D) said regulating members being so disposed that a long arm of one and the short arm of the other lie on the same side of said staff;

(E) at least one of said regulating members having a projection on its lateral surface defining the position of said member with respect to said scale on said arm section;

(1F a pair of parallel rods pivotally connected at their ends with said regulating members for retaining a symmetrical arrangement between said members.

References Cited by the Examiner UNITED STATES PATENTS 513,962 g 1/ 1894 Zwahlen 33-25 762,682 6/ 1904 Butts.

FOREIGN PATENTS 1,140,040 11/ 1955 France. 1,108,015 1/1956 France. 1,322,923 2/ 1963 France.

LOUIS J. CAPOZI, Primary Examiner.

LEO SMILOW, Examiner.

G. F. BAKER, Assistant Examiner. 

